The present invention relates to a vibration-proof stretcher for carrying an emergency patient to a nearby emergency hospital in an ambulance in which can be used to facilitate safe emergency treatment such as cardiopulmonary resuscitation and securing of the air passage of a patient lying on the stretcher.
There are different types of conventional stretchers used in an ambulance, such as stretchers a and b shown in FIGS. 6 and 7. Each of the stretchers a and b includes a chassis d having casters g provided with tires c, a bed frame e provided on the chassis divided into upper and lower portions for suporting the upper and lower parts of a patient lying on the stretcher, and a urethane mat f provided on lattices made of thin pipes of circular cross-section in the upper and lower portions of the bed frame (not shown in the drawings).
In recent years, the influence of vibration on a patient on such a stretcher has been regarded as a problem. Therefore, it has become important to address the question of how the patient on the stretcher can be carried more quietly. Maximum attention has consequently been paid to the conditions of the surface of the road and the traffic thereon in driving an ambulance to carry the patient on the stretcher. However, it has been reported that if the condition of the surface of the road is not good, the vibration of the ambulance is directly transmitted to the patient on the stretcher to make it likely that the patient undergoes pain or nausea to aggravate his condition, particularly when the patient is suffering from a serious disease, a heart problem, bone fracture or the like. One published paper reports that although external vibration on a human body is damped by the body if the frequency of the vibration is within a certain range, the amplitude of the vibration on the body is increased to resonance if the frequency of the vibration is equal to the natural frequency of the body. This paper reports that the resonance intensifies the jolt to the human body to further influence the body both psychologically and physiologically. The Japanese Association for Acute Medicine has announced a research result that reducing the influence of vibration of low frequency on the brain or other organs of a patient is an important factor in preventing the disease or injury of the patient from being aggravated.
It has been reported that even a healthy person feels very bad on such a conventional stretcher in a moving ambulance. The reason for the bad feeling is that the person is put on the stretcher with his head oriented in the same direction as the movement of the ambulance, which results in making him feel pressure in that direction at the time of stoppage or deceleration of the ambulance. Therefore, it is believed that the vibration on the patient on the stretcher and the movement of the affected part of his body not only give him mental restlessness or anguish, but also influence his convalescence from bone fracture, brain damage, cervical vertebra damage or the like.
Since the tires c of all four casters g of each of the conventional stretchers a and b are solidly or almost solidly made of rubber or plastic, vibration is scarcely absorbed by the tires. Since the bed lattices inside the bed frame e are made of thin pipes of circular cross-section, the vibration is not absorbed by the lattices at all.
Cardiopulmonary resuscitation, artificial respiration, heart massage and the like are emergency treatments. If such a treatment is not performed in time, the life of the patient cannot be expected to be saved, as shown by the Drinker survival curve .alpha. in FIG. 8. Therefore, such treatment is essential to enhance the rate of saving lives. If the patient lies directly on the urethane mat f of the stretcher, the upper part of his body sinks at the time of pressing thereon during heart massage so as to reduce the effect of the pressing. For that reason, a back plate h as shown in FIGS. 9 and 10 is interposed between the urethane mat f and the back of the patient P, as shown in FIG. 11, to perform the heart massage on him. However, since the patient and the back plate h are placed on the urethane mat f, the effect of the pressing during heart massage cannot always be made high enough to obtain a satisfactory result. Besides, if the stretcher, which is relatively heavy, is always provided with the back plate h, the stretcher becomes heavier. If the back plate h is always kept in the ambulance, since the stretcher is not always capable of carrying or accommodating the back plate, it is likely that the back plate must be fetched from the ambulance to the stretcher. Such fetching makes it impossible to perform an emergency treatment on the patient in time. Since securing the air passage of the patient requires the back plate h, it is necessary to take the trouble of fetching the back plate from the ambulance if the back plate is always kept in the ambulance.